Media adaptation is often used in the media streaming industry to deliver media content efficiently to different end users with different requirements and constraints. Given that nowadays video consumes most of Internet traffic, we hereby use video as a representative of the media of all formats. Our method and apparatus can be applied to other media formats.
To achieve the adaptation purpose, a particular media content is often prepared with different copies at different quality levels, for example, with copies having different combinations of spatial, temporal and bit rate resolutions. The existing media transport systems, including HTTP live streaming (HLS), Dynamic Adaptive Streaming over HTTP (DASH) or Motion Picture Experts Group (MPEG) media transport (MMT), are standardized to support adaptive streaming of the same content under the constraints imposed by the underlying access networks (i.e., delay, bandwidth, etc.) and the subscribed users (i.e., processing capability, user preferences, etc.).
To prepare copies of the same content at different quality levels, transcoding is commonly applied. Transcoding often includes the bit rate shaping from the high bit rate to the lower bit rate, and spatial/temporal resolution down-sampling from the Ultra High Definition to the High Definition or Standard Definition. Transcoding is also applied to adapt the content from one compression format to another (e.g., from the H.264/AVC compliant format to the HEVC compliant format), or to adapt the content within the same compression format to different quality levels.
In prior art, single input single output (SISO) adaption is typically deployed in a transcoding system. To prepare copies of the same content at different quality levels, the content has to be transcoded multiple times, one quality level at one time. In other words, to prepare copies of a content at for example 12 different quality levels, it requires transcoding of the same content for 12 times.
Our invention discloses a method and an apparatus that enables single input multiple output (SIMO) based transcoding by leveraging the content correlation between different quality levels and different compression formats.